The present invention relates to a non-volatile memory device and, more particularly, to a method of erasing which can shorten an erase operation time.
A non-volatile memory device is a device which retains data even though the supply of power is turned off. The flash memory device is a non-volatile memory device, which can be programmed, read, and erased many times through a program operation, a read operation and an erase operation. The erase operation is performed in order to delete stored data. The flash memory device can be classified into NOR flash memory devices and NAND flash memory devices. The erase operation of the NAND flash memory device is described below as an example.
In general, the cell array of the NAND flash memory device is classified into a single-plane type and a multi-plane type. Recently, as the level of integration and the memory capacity increase, the multi-plane type flash memory devices are widely used. The multi-plane type cell array is divided into a number of planes, and each of the planes includes a plurality of blocks. Each block includes a plurality of flash memory cells. The erase operation of the NAND flash memory device is performed on a block basis. At the time of the erase operation, the data of all memory cells included in a selected block are erased.
In the flash memory device, however, the program operation or the erase operation requires a long operating time compared with the operating time of other memory devices. Accordingly, an overall operating speed becomes relatively slow. In the case where a plurality of blocks are erased, a longer operating time is required, reducing the operating speed even more.